Compressor above condenser.

[Pawel_Wisnik]

Dear all, placing condenser with liquid receiver below compressor (~5 meters below) cause that installation does not function? Could you give me theoretical background concernig that issue please?

Regards

Pawel

[Brian_UK]

What does not function in your set up?

[lana]

Hi there,

Most probably you have a problem with liquid line which goes up 5m. You have to calculate the correct liquid line size and also required sub cooling so that a solid liquid line reaches the TEV.

Cheers

[Pawel_Wisnik]

Thx for expl.
Brg Pawe.

[Peter_1]

Dear all, placing condenser with liquid receiver below compressor (~5 meters below) cause that installation does not function? Could you give me theoretical background concernig that issue please?

Regards

Pawel

I don't see any problem with this setup.
But what IS your problem exactly?

[icecube51]

probably a low pressure problem on the LP inlet of the compressor..... i think?

Ice

[Pawel_Wisnik]

I don't see any problem with this setup.
But what IS your problem exactly?

Hi Peter,

I am forced to apply such layout in one of my sites within a couple a weeks to come, but in the meantime I heard an opinion that such setup did not work at all (but without explanation why it did not and what was the main problem), in my opinion there is no threats in it, but just to be sure I also dropped post here to see opinion from you, opinions that I appreciate very much .

Regards

Pawel

[Graham]

Possible accumulation of oil in receiver?

[Peter_1]

Make sure your line going up is large enough in diameter and if you want to use EEV's on your evaporators, try to install a subcooler (PHE) after your receiver.

[Aik]

Hi Peter,

I am forced to apply such layout in one of my sites within a couple a weeks to come, but in the meantime I heard an opinion that such setup did not work at all (but without explanation why it did not and what was the main problem), in my opinion there is no threats in it, but just to be sure I also dropped post here to see opinion from you, opinions that I appreciate very much .

Regards

Pawel

May be it was a case when compressor above condencer and receiver near the compressor (above condencer)?

[icecube51]

i am more thinking in the line of the compressor. problems whit the oil return. i don't think there was a refrig mensioned in this topic.

Ice

[benijoseph]

It should work, If it is not working give the pressure reading of LP and HP?

RGDs

[Scramjetman]

Provided the line size is right, it should work ok. Oil return can be a problem in condensers lower than the compressor particularly if the ambient conditions are low and head pressure control is poor. It often turns turns to sludge and sits in it occupying condenser area. Then a young tech comes along - sees no oil in the compressor and promptly adds another litre or two which also ends up in the condenser and so on it goes.

Best plan is to probably think about an oil separator to take care of the oil issues, make sure the lquid line has a low enough pressure drop and it should work fine.

[Pawel_Wisnik]

Make sure your line going up is large enough in diameter and if you want to use EEV's on your evaporators, try to install a subcooler (PHE) after your receiver.

Hi Peter,
I do so

Regards
Pawel

[Pawel_Wisnik]

i am more thinking in the line of the compressor. problems whit the oil return. i don't think there was a refrig mensioned in this topic.

Ice

Hi,
in my opnion there should not be a problem with oil, it flows freely down to condeser via discharge line then within condenser and liquid receiver dissolves in refrigerant.

[Peter_1]

Indeed, you will not face oil problems and surely not in the discharge and liquid lines. Liquid will fush out all the oil

[Aik]

In my opinion there is one problem of your system.
On summer ambient temperature may be high then room temperature where compressor situated. If compressor stop long time then its temperature may be smaller then condencer (and receiver). And refrigerant may migrate from receiver through condencer to head of compressor and condense there. When compressor start then may be hydraulic shock...

[icecube51]

always safe to mount an oiltrap evry 3mtr.

Ice

[Peter_1]

In upgoing liquid lines and flowing down discharge lines?

[Gingerair]

A non-return valve in the liquid line outlet from the condenser would not be a bad idea...

[icecube51]

in this case Peter, upgoing.

Ice

[nike123]

.........................

[Pawel_Wisnik]

In my opinion there is one problem of your system.
On summer ambient temperature may be high then room temperature where compressor situated. If compressor stop long time then its temperature may be smaller then condencer (and receiver). And refrigerant may migrate from receiver through condencer to head of compressor and condense there. When compressor start then may be hydraulic shock...

Hi
in this case machniery room always is at equal or a bit higher temperature than ambient, even in summer time.

[Peter_1]

An NRV will give you an additional DP in your liquid line and decrease overall system performance.
Why you need it anyhow? What is its benefit?

[Aik]

When compressor stop, if temperature of condencer and receiver will bigger than compressor, than refrigerant in liquid phase will evaporate in condencer and condence near more cold compressor (migrate).

Hi
in this case machniery room always is at equal or a bit higher temperature than ambient, even in summer time.

Then I don't see problems in your system...

[Aik]

A non-return valve in the liquid line outlet from the condenser would not be a bad idea...

In this system it would be better install check valve in the gas line on inlet to the condencer.

always safe to mount an oiltrap evry 3mtr.

Oiltraps don't stop migration...

[icecube51]

Oiltraps don't stop migration...

but whit the migration of the refrig, some oil will return, so the compressor will always have some oil to work whit.

Ice

[nike123]

I don't see any problem except that subcooling must be enough to compensate for 0,63 bar pressure drop due to liquid column of liquid refrigerant in 5 m pipe.
Oil is not of any concern if it is soluble with liquid refrigerant.

[Aik]

but whit the migration of the refrig, some oil will return, so the compressor will always have some oil to work whit.

Ice

In any case in Pawel_Wisnik's system oil trapes don't need on discharge line.

I don't see any problem except that subcooling must be enough to compensate for 0,63 bar pressure drop due to liquid column of liquid refrigerant in 5 m pipe.
Oil is not of any concern if it is soluble with liquid refrigerant.

I have the same opinion...

[Peter_1]

.........................

In the Suva example, gas line, 33.9 psi at bottom and 34.1 psi at the top

[nike123]

................................
Deleted!
You are right, it is mistake.

[Peter_1]

Why then the bottom weights less?

[nike123]

I think you misunderstand my last post. Deleted is my comment (which is wrong) that everything is OK on that Suva picture, because i did not paying attention at what is bottom and what is up.
Than I confirmed that you are right.

[garethjones10]

Hi

This is Gareth Jones

Most probably you have a problem with liquid line which goes up 5m. You have to calculate the correct liquid line size and also required sub cooling so that a solid liquid line reaches the TEV.

Regards,

Gareth
CNM ONLINE

[garethjones10]

Hi

Most probably you have a problem with liquid line which goes up 5m. You have to calculate the correct liquid line size and also required sub cooling so that a solid liquid line reaches the TEV.

Regards,

Gareth
CNM ONLINE